code-server/src/node/wrapper.ts at v3.10.1 · coder/code-server · GitHub

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import { field, Logger, logger } from "@coder/logger"

import * as cp from "child_process"

import * as path from "path"

import * as rfs from "rotating-file-stream"

import { Emitter } from "../common/emitter"

import { DefaultedArgs } from "./cli"

import { paths } from "./util"

const timeoutInterval = 10000 // 10s, matches VS Code's timeouts.

/**

* Listen to a single message from a process. Reject if the process errors,

* exits, or times out.

* `fn` is a function that determines whether the message is the one we're

* waiting for.

export function onMessage<M, T extends M>(

proc: cp.ChildProcess | NodeJS.Process,

fn: (message: M) => message is T,

customLogger?: Logger,

): Promise<T> {

return new Promise((resolve, reject) => {

const cleanup = () => {

proc.off("error", onError)

proc.off("exit", onExit)

proc.off("message", onMessage)

clearTimeout(timeout)

}

const timeout = setTimeout(() => {

cleanup()

reject(new Error("timed out"))

}, timeoutInterval)

const onError = (error: Error) => {

cleanup()

reject(error)

}

const onExit = (code: number) => {

cleanup()

reject(new Error(`exited unexpectedly with code ${code}`))

}

const onMessage = (message: M) => {

;(customLogger || logger).trace("got message", field("message", message))

if (fn(message)) {

cleanup()

resolve(message)

}

proc.on("message", onMessage)

// NodeJS.Process doesn't have `error` but binding anyway shouldn't break

// anything. It does have `exit` but the types aren't working.

;(proc as cp.ChildProcess).on("error", onError)

;(proc as cp.ChildProcess).on("exit", onExit)

})

}

interface ParentHandshakeMessage {

type: "handshake"

args: DefaultedArgs

}

interface ChildHandshakeMessage {

type: "handshake"

}

interface RelaunchMessage {

type: "relaunch"

version: string

}

type ChildMessage = RelaunchMessage | ChildHandshakeMessage

type ParentMessage = ParentHandshakeMessage

class ProcessError extends Error {

public constructor(message: string, public readonly code: number | undefined) {

super(message)

this.name = this.constructor.name

Error.captureStackTrace(this, this.constructor)

}

/**

* Wrapper around a process that tries to gracefully exit when a process exits

* and provides a way to prevent `process.exit`.

abstract class Process {

/**

* Emit this to trigger a graceful exit.

protected readonly _onDispose = new Emitter<NodeJS.Signals | undefined>()

/**

* Emitted when the process is about to be disposed.

public readonly onDispose = this._onDispose.event

/**

* Uniquely named logger for the process.

public abstract logger: Logger

public constructor() {

process.on("SIGINT", () => this._onDispose.emit("SIGINT"))

process.on("SIGTERM", () => this._onDispose.emit("SIGTERM"))

process.on("exit", () => this._onDispose.emit(undefined))

this.onDispose((signal, wait) => {

// Remove listeners to avoid possibly triggering disposal again.

process.removeAllListeners()

// Try waiting for other handlers to run first then exit.

this.logger.debug("disposing", field("code", signal))

wait.then(() => this.exit(0))

setTimeout(() => this.exit(0), 5000)

})

}

/**

* Ensure control over when the process exits.

public preventExit(): void {

;(process.exit as any) = (code?: number) => {

this.logger.warn(`process.exit() was prevented: ${code || "unknown code"}.`)

}

private readonly processExit: (code?: number) => never = process.exit

/**

* Will always exit even if normal exit is being prevented.

public exit(error?: number | ProcessError): never {

if (error && typeof error !== "number") {

this.processExit(typeof error.code === "number" ? error.code : 1)

} else {

this.processExit(error)

}

/**

* Child process that will clean up after itself if the parent goes away and can

* perform a handshake with the parent and ask it to relaunch.

class ChildProcess extends Process {

public logger = logger.named(`child:${process.pid}`)

public constructor(private readonly parentPid: number) {

super()

// Kill the inner process if the parent dies. This is for the case where the

// parent process is forcefully terminated and cannot clean up.

setInterval(() => {

try {

// process.kill throws an exception if the process doesn't exist.

process.kill(this.parentPid, 0)

} catch (_) {

// Consider this an error since it should have been able to clean up

// the child process unless it was forcefully killed.

this.logger.error(`parent process ${parentPid} died`)

this._onDispose.emit(undefined)

}

}, 5000)

}

/**

* Initiate the handshake and wait for a response from the parent.

public async handshake(): Promise<DefaultedArgs> {

this.send({ type: "handshake" })

const message = await onMessage<ParentMessage, ParentHandshakeMessage>(

process,

(message): message is ParentHandshakeMessage => {

return message.type === "handshake"

this.logger,

)

return message.args

}

/**

* Notify the parent process that it should relaunch the child.

public relaunch(version: string): void {

this.send({ type: "relaunch", version })

}

/**

* Send a message to the parent.

private send(message: ChildMessage): void {

if (!process.send) {

throw new Error("not spawned with IPC")

}

process.send(message)

}

/**

* Parent process wrapper that spawns the child process and performs a handshake

* with it. Will relaunch the child if it receives a SIGUSR1 or is asked to by

* the child. If the child otherwise exits the parent will also exit.

export class ParentProcess extends Process {

public logger = logger.named(`parent:${process.pid}`)

private child?: cp.ChildProcess

private started?: Promise<void>

private readonly logStdoutStream: rfs.RotatingFileStream

private readonly logStderrStream: rfs.RotatingFileStream

protected readonly _onChildMessage = new Emitter<ChildMessage>()

protected readonly onChildMessage = this._onChildMessage.event

private args?: DefaultedArgs

public constructor(private currentVersion: string) {

super()

process.on("SIGUSR1", async () => {

this.logger.info("Received SIGUSR1; hotswapping")

this.relaunch()

})

const opts = {

size: "10M",

maxFiles: 10,

}

this.logStdoutStream = rfs.createStream(path.join(paths.data, "coder-logs", "code-server-stdout.log"), opts)

this.logStderrStream = rfs.createStream(path.join(paths.data, "coder-logs", "code-server-stderr.log"), opts)

this.onDispose(() => this.disposeChild())

this.onChildMessage((message) => {

switch (message.type) {

case "relaunch":

this.logger.info(`Relaunching: ${this.currentVersion} -> ${message.version}`)

this.currentVersion = message.version

this.relaunch()

break

default:

this.logger.error(`Unrecognized message ${message}`)

break

}

})

}

private async disposeChild(): Promise<void> {

this.started = undefined

if (this.child) {

const child = this.child

child.removeAllListeners()

child.kill()

// Wait for the child to exit otherwise its output will be lost which can

// be especially problematic if you're trying to debug why cleanup failed.

await new Promise((r) => child!.on("exit", r))

}

private async relaunch(): Promise<void> {

this.disposeChild()

try {

this.started = this._start()

await this.started

} catch (error) {

this.logger.error(error.message)

this.exit(typeof error.code === "number" ? error.code : 1)

}

public start(args: DefaultedArgs): Promise<void> {

// Store for relaunches.

this.args = args

if (!this.started) {

this.started = this._start()

}

return this.started

}

private async _start(): Promise<void> {

const child = this.spawn()

this.child = child

// Log both to stdout and to the log directory.

if (child.stdout) {

child.stdout.pipe(this.logStdoutStream)

child.stdout.pipe(process.stdout)

}

if (child.stderr) {

child.stderr.pipe(this.logStderrStream)

child.stderr.pipe(process.stderr)

}

this.logger.debug(`spawned inner process ${child.pid}`)

await this.handshake(child)

child.once("exit", (code) => {

this.logger.debug(`inner process ${child.pid} exited unexpectedly`)

this.exit(code || 0)

})

}

private spawn(): cp.ChildProcess {

// Use spawn (instead of fork) to use the new binary in case it was updated.

return cp.spawn(process.argv[0], process.argv.slice(1), {

env: {

...process.env,

CODE_SERVER_PARENT_PID: process.pid.toString(),

NODE_OPTIONS: `--max-old-space-size=2048 ${process.env.NODE_OPTIONS || ""}`,

stdio: ["inherit", "inherit", "inherit", "ipc"],

})

}

/**

* Wait for a handshake from the child then reply.

private async handshake(child: cp.ChildProcess): Promise<void> {

if (!this.args) {

throw new Error("started without args")

}

await onMessage<ChildMessage, ChildHandshakeMessage>(

child,

(message): message is ChildHandshakeMessage => {

return message.type === "handshake"

this.logger,

)

this.send(child, { type: "handshake", args: this.args })

}

/**

* Send a message to the child.

private send(child: cp.ChildProcess, message: ParentMessage): void {

child.send(message)

}

/**

* Process wrapper.

export const wrapper =

typeof process.env.CODE_SERVER_PARENT_PID !== "undefined"

? new ChildProcess(parseInt(process.env.CODE_SERVER_PARENT_PID))

: new ParentProcess(require("../../package.json").version)

export function isChild(proc: ChildProcess | ParentProcess): proc is ChildProcess {

return proc instanceof ChildProcess

}

// It's possible that the pipe has closed (for example if you run code-server

// --version | head -1). Assume that means we're done.

if (!process.stdout.isTTY) {

process.stdout.on("error", () => wrapper.exit())

}

// Don't let uncaught exceptions crash the process.

process.on("uncaughtException", (error) => {

wrapper.logger.error(`Uncaught exception: ${error.message}`)

if (typeof error.stack !== "undefined") {

wrapper.logger.error(error.stack)

}

})

code-server/src/node/wrapper.ts at v3.10.1 · coder/code-server · GitHub

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